This invention relates to mobile storage units, particularly those units moved by hand, and most particularly to those mobile storage units that have some type of locking means to prevent or at least reduce the incidence of accidental closure of an aisle.
It is well known to equip mobile filing and storage systems with locking mechanisms. The disadvantage of early locking mechanisms, though, was that they were required to be set to the locked mode only when the storage unit is at the desired location along the track. One example of structure such as this is Peterman, U.S. Pat. No. 4,523,794, which shows a locking mechanism used in conjunction with a handwheel by which the storage unit is moved along tracks on the floor. While the locking mechanism there disclosed operates very well, because of the details of the structure it is limited to use with the handwheel, besides the other disadvantages mentioned above. Another disadvantage of this type of locking mechanism is that it locks the storage unit against movement in both directions. Once the mechanism is engaged, it is not possible to move the storage unit in either direction. The necessity of always unlocking the storage unit before moving it and then re-locking it at the new location may be inconvenient and undesirable, particularly if only small increments of motion are required.
Another locking mechanism is shown in Peterman, U.S. Pat. No. 4,607,896. This mechanism includes a toothed rack positioned along the track on which the mobile storage unit moves. Again this arrangement is very effective in conjunction with the structure disclosed there, because it does not require a handwheel as indicated with respect to the earlier invention, and because even when engaged to prevent movement in one direction it permits movement in the other. But it is disclosed to be engaged by action of a lock and key. In certain instances it may be more convenient to have a lock mechanism that engages automatically, without any need for direct intervention or intentional action by a user.
This invention relates to improvements to the locking mechanisms described above, and to solutions to some of the problems raised or not solved thereby.